1. Field of the Invention
The present invention relates to orthopedic instrumentation and more particularly relates to an ankle clamp apparatus which allows a surgeon to use one hand to attach the ankle clamp as part of an overall tibial alignment assembly. More particularly, the present invention relates to an improved ankle clamp apparatus with a locking feature that secures movable arm portions of the clamp in an open position until the clamp is positioned for use at which time the locking feature may be disengaged from the arms, allowing the clamp to tighten around the ankle of the patient.
2. General Background
During total knee replacement, the upper or proximal portion of the tibia is cut away using a saw such as a reciprocal saw. The surgeon places the saw on the top of a cutting block that is positioned at the proximal end of the tibia. The cutting block provides a surface that supports the saw blade in a desired, steady position. Placement of tibia instrumentation and cutting block is critical because the block must be positioned correctly and held firm during the entire cutting operation so that an accurate cut is made.
One way to mount the cutting block and its associated instrumentation is to actually mount the cutting block to an intermedullary canal, that occupies the hollowed inside portion of the tibia, so that the cutting block lies adjacent to the bone to be sawed.
A second way to correctly align the cutting block is through an external or extramedullary alignment assembly. These devices include extendable telescoping, or solid rod assemblies with a lower end portion carrying an ankle clamp that grasps the patient's ankle. By holding the patient's leg externally and very firmly with assist from the ankle clamp, the cutting block can be positioned and held steady during the cutting so that the cuts are made precisely by the surgeon.
Extramedullary alignment assemblies include the extendable telescoping rod for the purpose of adjusting the entire instrumentation assembly to the length of a particular patient's leg. Similarly, extramedullary alignment assemblies which include a solid non-extendable rod permit the cutting block to slide thereon and be selectively positioned to a desired clamping location. Additionally, lateral adjustments are available for moving the extramedullary alignment assembly away from or toward the patient's tibia.
Presently, ankle clamps are commercially available which include a frame (also known as a "Y-block") with a pair of arms pivotally attached to the frame on opposite sides. These arms are spring loaded so that they are biased to a closed clamping position until opened by the surgeon. These prior art clamps do not provide a means to maintain the arms in an open position, and because there are two arms, two hands are required to open these prior art type ankle clamps.